Tina's suggestion really is great. That is exactly what I do each time I find an interesting business opportunity or a new business venture (which is quite often).

I write out a business plan each time to see if it's even worth pursing. What may seem like a great business initially, doesn't look so appealing when you break it down methodically and see the income potential. Don't just focus on sales potential, but on profit. Figure all of your expenses, startup and ongoing monthly expenses to get a complete picture.

Then look at your competition and think about a marketing plan. What about your customer base? Will the demographics work?

It's amazing how much information you will find when you start putting it down in writing.